Jupiter and Saturn:
I have removed some of the items in the lists, so ignore numbering of items.
Jupiter is the largest planet in the solar system. It is larger than all the other planets put
together.
Jupiter has more than 60 moons. Four of which would be considered large. (Io, Europa,
Ganymede, and Callisto)
Jupiter is about 5Au from the Sun.
Saturn is the second largest planet in the solar system.
Jupiter has more mass than all other planets combined.
Jupiter is about 300 Earth masses, Saturn is about 100 Earth masses.
Saturn has one large Moon (Titan). Saturn is about 10 AU from the Sun.
1) What is the composition of Saturn’s rings? Saturn’s rings are composed many thin
rings each orbiting at its own speed. The closer the ring is to the planet, the faster the
material in that ring is orbiting.
Jupiter and Saturn exhibit differential rotation.
2) What is going on in Jupiter’s red spot? Jupiter’s red spot is a rotating storm that is like
a wheel between two bands of air moving in opposite directions. Jupiter’s red spot is at
least several hundred years old. It is about 5 earth diameters in size.
3)What does the chemical composition of Jupiter’s atmosphere imply about the planet’s
origin. The chemical composition of the atmosphere indicates that it has about the same
percentages of hydrogen and helium as the Sun does. This supports the nebular
hypothesis that they formed from the same cloud.
4) How do astronomers know about the deep interiors of Jupiter and Saturn? The
oblateness of Jupiter and Saturn are indicators of the sizes of their rocky cores. Their
densities also give information about this. Finally, the magnetic fields indicate they have
liquid metallic hydrogen.
5) How do Jupiter and Saturn generate their intense magnetic fields? Both planets are
rotating very rapidly (they rotate in approximately 10 hours), and they both have liquid
metallic hydrogen in their interiors.
6) How was it discovered that Saturn has rings? First Galileo saw lumps on Saturn, then
several decades later Christiaan Huygens used a better telescope to determine the lumps
were rings.
7)Are Saturn’s rings solid bands that encircle the planet? No they are rings of small
particles (snowball sized on average). The rings do not intermingle very much.
8) How uniform and smooth are Saturn’s rings? Actually Saturn’s rings are composed of
many thin ringlets that do not interact much, so the rings are not smooth or uniform.
9) How do Saturn’s Moons affect the rings? Some of the Moons cause gaps in the rings.
The Cassini division is a gap in the rings caused by the Moon Mimas. Some of the
moons act as shepards for the rings.
10) Which planet, Mars or Jupiter, passes closer to the Earth? Mars passes closer—it
orbits between Earth and Jupiter. On which planet is it easier to see details? Well, Jupiter
is so much larger that it appears about twice as big in a telescope even though it is farther
away.
11) How did astronomers learn that Jupiter is a gaseous planet? Jupiter’s atmosphere
exhibits differential rotation in which the air at the poles takes about 5 minutes longer to
complete a rotation than the air at the equator.
12) How large is the rocky core of a Jovian planet? They all have rocky cores of about 5
to 10 Earth masses.
13) Compare Jupiter’s chemical composition with that of the Sun. They are about the
same—Hydrogen and Helium. This supports the nebular hypothesis.
14) Is the chemical composition of Jupiter as a whole the same as that of its atmosphere?
No, because Jupiter as a whole has heavy elements in its rocky core that are too dense to
float in its atmosphere.
15) What are the belts and zones in the atmospheres of Jupiter and Saturn? The belts are
the darker areas and the zones are the lighter areas. The belts are areas where warm air is
rising, the zones are areas where higher cool air is sinking.
17) Compare and contrast the source of energy for the motions of air in the atmospheres
of Jupiter and Saturn to that of Earth. Earth gets energy for its atmosphere from the Sun.
Jupiter and Saturn get most of the energy for their atmospheres from the internal energy
of the planet.
18) Compare the internal energy sources of the two planets that produce this emission.
Jupiter and Saturn are still warm internally from the energy they gained (from
gravitational contraction) during their formation. So both planets generate heat this way.
19) Why are Jupiter and Saturn oblate? Because it is rotating quickly. What do
astronomers learn from the value of its oblateness? They can determine the size of the
rocky core from the planet’s oblateness.
20) What is liquid metallic Hydrogen? It is hydrogen that has been compressed enough
that it liquefies—it then takes on the characteristics of a metal. What is its significance
for Jupiter? It provides the liquid metal conductor that carries the current that produces
Jupiter’s magnetic field.
21) Explain why Saturn is more oblate than Jupiter even though Saturn rotates a little
more slowly. Saturn has less mass and so a weaker gravity so when it spins it bulges out
more at the equator.
22) Why is Saturn’s magnetosphere less extensive than Jupiter’s? Because Saturn is
smaller, has less liquid metallic hydrogen, and is rotating a little slower.
23) How do Jupiter’s rings differ from Saturn’s? Jupiter’s rings are much smaller, and
they are composed of dark particles that reflect little light.
24) What is the Roche limit? If a moon gets within the Roche limit (a distance) of a
planet, tidal forces from the planet will pull the moon apart.
Uranus and Neptune:
Uranus and Neptune are 20 AU and 30 AU from the Sun respectively.
They are both about 4 to 5 Earth diameters in size and about 15 Earth masses.
2)What gives Uranus its distinctive bluish-green color? Methane in its atmosphere.
3)Why are the clouds on Neptune much more visible than those on Uranus? Because
Neptune has internal heating—astronomers believe it is still contracting gravitationally-and consequently has a more dynamic atmosphere. This gives it more clouds and more
weather.
5)Why are the rings of Neptune and Uranus so difficult to see? Because they are very
thin (less than 10 miles wide) and they are as dark as lumps of coal.
6) Do the Moons of Uranus and Neptune show any signs of geologic activity? Some of
the moons have regions with cracks, ice-lava flows, and no craters. These are all
indications that there was geologic heating in their past. Astronomers believe some of
the moons were tidally heated.
8)Why was the discovery of Neptune rated as a great triumph of science while those of
Uranus and Pluto were not? Because astronomers predicted the existence of Neptune and
its location after applying Newton’s laws to the motion of Uranus. Both Uranus and
Pluto were found more or less by accident.
11)Why are Uranus and Neptune distinctly blue-green in color while Jupiter and Saturn
are not? Because Uranus and Neptune have significant amounts of methane in their
atmosphere; this is what gives them the color. Jupiter and Saturn do not have much
methane in their atmospheres.
13) Why do astronomers think that Triton was captured by Neptune? First it is in a
retrograde orbit—it is the only large moon in the solar system that does this. Second, it is
orbiting Neptune on a path that is tilted at 23 degrees to the plane of Neptune’s equator.
It is the only large moon in the solar system that is doing this. These are both strong
indicators that Triton was captured.